Brake warning light system


runsmom

New member
i have a 71 westy that the brakes were so tight they wouldnt move..i adjusted them from the back plate so the wheels are free again but i
cannot get the brake indicator light to go off now..when the wheels were locked up it wasnt on..i have tried to adjust them on both sides a
click at a time..theyre barely touching now but the indicator light will not go off.i adjust and adjust it wont go off . . .any suggestions?

[ 07-12-2001: Message edited by: Capt. Mike ]
 

Capt. Mike

Moderator
The brake light is not related to brake adjustment. According the The Bentley diagram for your car, the brake warning light is activated by one of the two hydraulic brake failure switches in the master cylinder.

I would assume the brake work has caused some problem with the system, a common enough occurance, especially in an older system. Backing off the brakes may have forced fluid back into the master cylinder beyond its capacity and caused a failure or switch problem. See the "Brake fluid changes" topic in this forum for some related issues.

Later Type II's had a seperate mechanical switch that worked off the emergency brake arm, but that too would not be related to wheel adjustment.

[This message has been edited by Capt. Mike (edited 10-10-2000).]
 

CGOTTS

New member
Your brake light problem will be the pressure switch on your brake master cylinder. This reservoirs were a two section unit. One would work the front brake shoes, and the other for the rears. If you had a line break, then you wouldn't lose all your brakes. So check your switches on the brake master cylinder. If you have an ohm meter - if you get continuity touching the leads on either switch, then that is the switch. You could also have a bad master cylinder, and the switch is working properly - bleed all the wheel cylinders and see if they all do. Good luck and hope this helps. CGOTTS

[This message has been edited by Capt. Mike (edited 09-22-2000).]
 

Capt. Mike

Moderator
Transferred from another post to consolidate same subject.

Brake warning Light Always on 78 Westy

AllenGrant Junior Member # 431 posted 10-18-2000 07:24 PM

Hi,

My brake warning light is always on in my 78. This happened about 1 month ago. The brakes seem fine. Could this be the emergency brake switch that the lever pushes in when disengaging the brake? OR should I be looking elsewhere? Am I in danger? Please advise. Thanks

Allen Grant

CGOTTS Member # 168 posted 10-18-2000 11:16 PM

Allen,

Anytime you get a warning light - it needs to be investigated! Normally, the brake warning light means that there could be a problem with your master cylinder. These master cylinders are a two system type, in that one half of it works the front discs, and the back half works to rear drums. There are two brake light switches on the master cylinder which is in parallel with the brake lights, so that if one section fails, you will still have the other section and brake light activation. On this same switch is a set of contacts that basically tells the brake warning light to come on if there is no pressure in that section. So, with a warning light for the brake coming on, it needs to be checked. It could be as simple as a bad switch, or even worse, a bad master cylinder. Normally if the bus still seems to brake well, you are probably only feeling the disc brakes, since they do most of the breaking anyway. Hope this helps and good luck.

CGOTTS
 

Capt. Mike

Moderator
An off-site or improper post did ask a legitimate question for older VW owners.

What is the little red button on the dash with a "B" in it that lights up when you push it?

Older VW's in the Type I & II era had a brake failure warning light. It was typically in the middle of the dash, red and had a "B" inside a circular graphic. Pressing the button tested the light.

It's function was explained in the owners manual. They light & switch show up in the appropriate model year wiring diagrams and has a test & repair section in the Type II Bentley. /infopop/emoticons/icon_rolleyes.gif
 

Capt. Mike

Moderator
Last week, I was hauling my Syncro up about 100 miles away. It was in the trailer because I had removed lights and bumper in prep for a repair. Tow truck, trailer & Westy are about 16,300 lb. As is reached the bottom of my very steep drive, the Brake light was on. This is the same light as used for the parking brake not released. Checked that, shut off & restarted the engine to reset any sensors. No luck. Drove to a level spot and went through the same secenario with the same results. Now the ABS light is on. A visual inspection found drippings of brake fluid. I still had some brakes, but by now were spongy. I returned, disconnected the trailer, and put the truck in my shop. Sure enough, major leak on the fixed metal line running to the rear brakes. I'm lucky; it could have failed as I hit I-85 with rush hour traffic and construction.
icon_confused.gif
Don't ignore a warning light! Warning light failures are far rarer than failure of the system they are monitoring.
 
M

mjname

Guest
I just had my braks adjusted at Brake Masters, the emergency brake now works great and my breaks are no longer spongy. However my brake indicator light on dash no longer works and my rear brake lights no longer work either.

I'm going to bleed the breaks tomorrow morning as suggested in first post. Has anyone else had a similar problem and did this fix it?

Thanks
Matthew Name
 
M

mjname

Guest
Sorry, 83 westy air cooled. The adjustment was to the rear drums.

I just re-bleed all 4 wheels and my brake lights still don't work. I think I will have to take it to the shop and have new switches put into the master brake cylinder. Unless anyone has a suggestion thanks
 

Capt. Mike

Moderator
Again, brake lights and the physical adjustment of the brakes at the wheels are NOT related. The closest the mechanic gets to the brake light system is filling the master cylinder!


Air in the master cylinder could -- that's a theoretical, not common -- be an air pocket that prevents the pressure from activating the switch. So check your electrical side, including testing the switches. Do your 4-ways & turn indicator lights work? That isolates the problem to the brake light circuits in your wiring diagram since they use the same filiment and ground.
 
M

mjname

Guest
I double checked to make sure that the 4 way and turn signals worked. I bled the brakes and it did not cure the problem of no brake lights. I replaced the first (back) switch on the brake master cylinder and YAHOO! Brake Lights!!!! Glorious brake lights. Thanks for your help and the clarity. Thanks again for a wonderful forum.

Matthew
 

Capt. Mike

Moderator
This is a chance for me to get back on my soapbox about changing brake fluid every 2 years! Since it was a working switch that quit during a brake bleeding job, I'd be willing to bet that the brake work stirred up debris and clogged the tiny orifice to the switch. Add that it has probably been gunked & varnished up from not being done all it's life, and you have the recipe for brake problems.

The most dirt, oxidation and moisture in a brake system is down at the calipers or cylinders because they are in & out through the seal hundreds of times a day in a very dirty environment. But . . . the master cylinder is still a breathing system, thus subject to hygroscopic moisture and dirt or debris from removing the cap during services and the fill process.

Change fluid every 2 years, using utmost cleanliness around the master cylinder. Glad the site was a help.
 

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